Typhoon Songda strengthened to a supertyphoon after battering the Philippines and headed for Japan on a track that may pass over the crippled Fukushima nuclear plant by May 30, a U.S. monitoring center said.

Songda’s winds increased to 241 kilometers (150 miles) per hour from 213 kph yesterday, the U.S. Navy Joint Typhoon Warning Center said on its website. The storm’s eye was about 240 kilometers east of Aparri in the Philippines at 8 a.m. today, the center said. Songda was moving northwest at 19 kph and is forecast to turn to the northeast and cross the island of Okinawa by 9 p.m. local time tomorrow before heading for Honshu.